Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 04-26-2017, 12:00 AM   #1 (permalink)
EcoModding Lurker
 
Join Date: May 2016
Location: Virginia
Posts: 44
Thanks: 1
Thanked 20 Times in 15 Posts
Are side skirts worth it ?

Hi All,

Looking at many over the road tractor trailers I have noticed that many trailers are equipped with side skirts that help fuel economy.

I was wandering around Lowes the other day and found that they sold rolls of pretty thick plastic like landscape edging that I thought would make for good side skirts.... 20 foot roll or black composite edging for $24.98 item number 514744...it looked to be about 3.5 inches tall (I wished it was taller so the skirts would go closer to the ground)

Has anybody here experimented with side skirts? Is lower better or is 3.5 inches better than nothing?

How do you think they would do without modding the front air dam?

For mounting, I was thinking of welding some bolts onto the seam that runs along the bottom of my Jetta (the same seam that the factory jack raises the car from) and then just drilling the corresponding holes on the side skirt for a simple bolt on operation.

Any thoughts and or experience with this?

Thanks

Andrew

__________________
2003 Jetta TDI Wagon, 5 sp, 210K miles, Stock.....for now!
  Reply With Quote
The Following User Says Thank You to Andyinchville1 For This Useful Post:
aerohead (04-29-2017)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 04-26-2017, 08:24 AM   #2 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 4,158
Thanks: 120
Thanked 2,790 Times in 1,959 Posts
Please post photos of your vehicle and provide measurements on the ground clearance of the front chin spoiler and the height on the sides where you are looking to install the skirting.

I'm just thinking this is a case by case thing, not sure there are many advantages if the side skirts end up lower than the front. You don't want to go into hovercraft mode on the highway - just saying.
__________________
George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
  Reply With Quote
The Following User Says Thank You to kach22i For This Useful Post:
mcrews (04-30-2017)
Old 04-26-2017, 10:29 AM   #3 (permalink)
Focused on MPG
 
Join Date: Apr 2009
Location: Uphill from the river!
Posts: 429

Marinator - '06 Mercury Mariner Premier
90 day: 10.61 mpg (US)

SILVER BULLET - '19 DODGE GRAND CARAVAN GT
90 day: 18.08 mpg (US)

Myrtle - Wife's JKU - '12 Jeep JK Unlimited Sport
90 day: 15.51 mpg (US)
Thanks: 122
Thanked 126 Times in 100 Posts
Home Depot if one in your area, they have the 5in tall edging, they also carry the Corrugated Plastic, Lowes doesn't, at least in my area
__________________







Staying Focus'd on MPG
  Reply With Quote
The Following User Says Thank You to ECO-AKJ For This Useful Post:
mcrews (04-30-2017)
Old 04-26-2017, 10:51 AM   #4 (permalink)
Master EcoModder
 
Join Date: Feb 2010
Location: Elmira, NY
Posts: 1,781
Thanks: 319
Thanked 355 Times in 297 Posts
Air dams and side skirts may be used to reduce drag or increase down force. Trailers use skirts to divert air flow away from rear axles and tires. You may not get 4 inches of snow on the road in Virginia but make sure you have an easy way to use a jack to raise the car.
  Reply With Quote
Old 04-26-2017, 01:37 PM   #5 (permalink)
Master EcoModder
 
gumby79's Avatar
 
Join Date: Dec 2014
Location: Butte, Montana
Posts: 725

little jona - '91 Dodge D 250 first gen cummins LE
Team Streamliner
90 day: 23.4 mpg (US)

Little Jona airo modded - '91 Dodge RAM 3/4 TON D 250 2×4 AUTO
Pickups
Team Cummins
90 day: 18.5 mpg (US)

The Salted Hound Jenny. - '87 Dodge Ram 50/D-50 5sp 4X4
90 day: 20.24 mpg (US)

Jona Allison aero - '91 Dodge Ram D-250 Le
90 day: 20.76 mpg (US)
Thanks: 208
Thanked 427 Times in 278 Posts
CARB (California Air Resources Bord) is now(2009 all exemptions expire January 1, 2018) REQUIRES skirts and low rooling resistance tires on all 53' box/refer trailers .
http://m.truckinginfo.com/article/25...pliant-trailer
Why ? Because they work 4% improvement at 55mph (California truck speed limit) and bigger the faster you go (70-85mph Mt. , Id. ,Ut. Truck speed limit)

From what I have read .
3" off the deck/ground , or
1/2" lower than the lowest thing hanging down.
Any thing lower has a diminishing return till about 3/4" off the ground.
Eg . Many new cars have less air dam (more clearance) in the center were the suspension duse not hang down. And larger wheels that alow more ground clearance under the lower control arm.


Side skirts only should help but much less effective , and like kach22i stated could destabilize your rig under the right wind / driving conditions.
__________________
1st gen cummins 91.5 dodge d250 ,HX35W/12/6 QSV
ehxsost manafulld wrap, Aero Tonto
best tank: distance 649gps mi 24.04 mpg 27.011usg
Best mpg : 31.32mpg 100mi 3.193 USG 5/2/20


Former
'83 GMC S-15 Jimmy 2door 2wd O/D auto 3.73R&P
'79 Chevy K20 4X4 350ci 400hp msd custom th400 /np205. 7.5-new 14mpg modded befor modding was a thing
87' Hyundai Excel
83 ranger w/87 2.9 L FI2wd auto 18mpg on the floor
04 Mitsubishi Gallant 2.4L auto 26mpg
06 Subaru Forrester XT(WRX PACKAGE) MT AWD Turbocharged 18 plying dirty best of 26mpg@70mph
95Chevy Blazer 4x4 auto 14-18mpg
04 Chevy Blazer 4x4 auto 16-22mpg


  Reply With Quote
Old 04-26-2017, 02:58 PM   #6 (permalink)
EcoModding Lurker
 
Join Date: May 2016
Location: Virginia
Posts: 44
Thanks: 1
Thanked 20 Times in 15 Posts
Quote:
Originally Posted by kach22i View Post
Please post photos of your vehicle and provide measurements on the ground clearance of the front chin spoiler and the height on the sides where you are looking to install the skirting.

I'm just thinking this is a case by case thing, not sure there are many advantages if the side skirts end up lower than the front. You don't want to go into hovercraft mode on the highway - just saying.
HI,

I can't seem to get pics on here but my car is a standard (well except for some of my mods!) 2003 VW jetta TDI 5 sp Station Wagon.

The approx dist from the ground to the underside of the front "valence" is about 6 inches off the gound

Jettas have a plastic engine compartment belly pan...That is behind the front valence somewhat but it it about 4 inches of clearance under there to the ground

The front side just ahead of the front tires is about 4 inches.

just behind the front tires is about 6 inches to the ground

just in front of the rear tires is about 8.5 inches to the ground

the underside height at the end of the rear bumper is about 13 inches to the ground.

The lowest point under the car is the engine belly pan....it is shaped to seemingly deflect air towards the ground.

Hope this helps.

Andrew
__________________
2003 Jetta TDI Wagon, 5 sp, 210K miles, Stock.....for now!
  Reply With Quote
Old 04-26-2017, 03:08 PM   #7 (permalink)
EcoModding Lurker
 
Join Date: May 2016
Location: Virginia
Posts: 44
Thanks: 1
Thanked 20 Times in 15 Posts
Quote:
Originally Posted by Grant-53 View Post
Air dams and side skirts may be used to reduce drag or increase down force. Trailers use skirts to divert air flow away from rear axles and tires. You may not get 4 inches of snow on the road in Virginia but make sure you have an easy way to use a jack to raise the car.
If I end up bolting side skirts to the seam running the length of the side body (a perfect place to attach the side skirts) I would have to make the last few inches in the area immediately behind the front wheels and in front of the rear wheels unboltable so I could flex the skirt out of the way since that same seam is used by the factory jack to lock onto to raise the car in the event of a flat.

I think ideally the side skirts would have to be at an angle and go under the car to where the belly pan is at its lowest and then angle outward diagonally until just ahead of the rear tires...i.e. if one were looking from the roof of the car downward the would in theory "see" a "v" just behind the engine belly pan extending diagonally to just ahead of the rear tires.

However, for ease of doing I wonder if simply bolting to the underbody seam would help much....I can't help but think that at least it should help at least
some although maybe not as optimally as the "v" idea above.
__________________
2003 Jetta TDI Wagon, 5 sp, 210K miles, Stock.....for now!
  Reply With Quote
Old 04-26-2017, 05:03 PM   #8 (permalink)
Too many cars
 
Gasoline Fumes's Avatar
 
Join Date: Oct 2009
Location: New York State
Posts: 1,568

CRXFi - '88 Honda CRX XFi

Insight 256 - '00 Honda Insight
Team Honda
Gen-1 Insights

Insight 5342 (no IMA) - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 66.3 mpg (US)
Thanks: 1,316
Thanked 781 Times in 465 Posts
I put side skirts on my Civic Wagon a few years ago. Just vertical coroplast. I never did any tuft testing before installing them, but I did it after. They seem to be limiting how much air goes under the car. I also have a front splitter/airdam. The side skirt height I went with was to clear speed bumps.

Attached Thumbnails
Click image for larger version

Name:	skirt-tufts.jpg
Views:	1922
Size:	33.2 KB
ID:	21634  
__________________
2000 Honda Insight
2000 Honda Insight
2000 Honda Insight
2006 Honda Insight (parts car)
1988 Honda CRXFi
1994 Geo Metro

  Reply With Quote
The Following 3 Users Say Thank You to Gasoline Fumes For This Useful Post:
101Volts (06-06-2017), BamZipPow (04-28-2017), Grant-53 (04-27-2017)
Old 04-27-2017, 04:31 AM   #9 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,562
Thanks: 7,738
Thanked 8,554 Times in 7,041 Posts
Stance it.

https://mulpix.com/instagram/mk4_jetta_wagon.html
  Reply With Quote
The Following 2 Users Say Thank You to freebeard For This Useful Post:
ChopStix (04-27-2017), Grant-53 (04-27-2017)
Old 04-29-2017, 12:44 PM   #10 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 15,861
Thanks: 23,922
Thanked 7,207 Times in 4,640 Posts
skirts

Quote:
Originally Posted by Andyinchville1 View Post
Hi All,

Looking at many over the road tractor trailers I have noticed that many trailers are equipped with side skirts that help fuel economy.

I was wandering around Lowes the other day and found that they sold rolls of pretty thick plastic like landscape edging that I thought would make for good side skirts.... 20 foot roll or black composite edging for $24.98 item number 514744...it looked to be about 3.5 inches tall (I wished it was taller so the skirts would go closer to the ground)

Has anybody here experimented with side skirts? Is lower better or is 3.5 inches better than nothing?

How do you think they would do without modding the front air dam?

For mounting, I was thinking of welding some bolts onto the seam that runs along the bottom of my Jetta (the same seam that the factory jack raises the car from) and then just drilling the corresponding holes on the side skirt for a simple bolt on operation.

Any thoughts and or experience with this?

Thanks

Andrew
There is a risk that VW has already optimized the skirts.They've known of their significance since the 1970s.Hucho was part of that.

__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com